High strength extrusion alloy

ABSTRACT

This disclosure provides an aging process or a method for aging aluminum alloys. For example, the aging process can be performed on 6xxx Al-Si-Mg-Cu aluminum alloys to result in production of such alloys with improved intergranular corrosion (IGC) resistance. The disclosed aging process includes subjecting a solution heat treated and quenched 6xxx aluminum alloy to a temperature above an aging hardening temperature of said alloy but below the solution heat treatment temperature for a short period of time, and then subjecting said alloy to an aging heat treatment at an aging hardening temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Application No.: 63/334765, filed on Apr. 26, 2022; which is herein incorporated by reference in its entirety.

FIELD

The present disclosure relates to alloys, more particularly to aluminum alloys, and more particularly to aluminum extrusion alloys.

BACKGROUND

Aluminum alloys are widely used in various industries due to their favorable properties, including low density, high strength-to-weight ratio, and good corrosion resistance. Some aluminum extrusion alloys are used in the automotive industry because the aluminum extrusion alloys can achieve very complex shapes and profiles. One such alloy is the 6xxx series. The 6xxx series aluminum alloys, which include aluminum-magnesium-silicon (Al-Mg-Si) alloy systems are popular for their excellent combination of strength, formability, and weldability. The 6xxx alloy series may be used for automobile body structure, suspension and driveline components. Aluminum extrusion alloys, such as 6xxx extrusion alloys may allow for innovative light-weight design with integrated functions. There is a general a need for improved extrusion alloys.

SUMMARY

Following summary is a high-level overview of various aspects and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings, and each claim.

The present disclosure provides improvements to methods for manufacturing and improved 6xxx series aluminum alloy that are superior to conventional alloys. The alloy composition comprises aluminum (Al), magnesium (Mg), silicon (Si), and one or more additional elements, such as copper (Cu), zinc (Zn), and/or manganese (Mn).

In some aspects, the techniques described herein relate to a method including: subjecting an alloy to a first temperature for a first time duration, wherein the first temperature is greater than an aging hardening temperature of the alloy and below a solution heat treatment temperature; and subjecting the alloy to a second temperature for a second time duration.

In some aspects, the techniques described herein relate to a method, further including: subjecting the alloy to a solution heat treatment at the solution heat treatment temperature, prior to the subjecting the alloy to the first temperature.

In some aspects, the techniques described herein relate to a method, wherein the second temperature is an aging hardening temperature.

In some aspects, the techniques described herein relate to a method, wherein the alloy includes a solution heat treated and quenched alloy.

In some aspects, the techniques described herein relate to a method, wherein the alloy includes a 6xxx aluminum alloy.

In some aspects, the techniques described herein relate to a method, wherein the alloy includes a 6xxx Al-Si-Mg-Cu aluminum alloy.

In some aspects, the techniques described herein relate to a method 1-6, further including: obtaining a resulting alloy, wherein the resulting alloy has an improved intergranular corrosion (IGC) resistance.

In some aspects, the techniques described herein relate to a method, wherein the first temperature is from 200° C. to 210° C.

In some aspects, the techniques described herein relate to a method, wherein the first time duration is from 5 minutes to 20 minutes.

In some aspects, the techniques described herein relate to a method, wherein the second temperature is from 150° C. to 200° C.

In some aspects, the techniques described herein relate to a method, wherein the second time duration is from 30 minutes to 3 hours.

In some aspects, the techniques described herein relate to a method including:

subjecting an aluminum alloy to a first temperature for a first time duration; and subjecting the aluminum alloy to a second temperature for a second time duration, wherein the first temperature is higher than the second temperature, wherein the first time duration is from 5 minutes to 20 minutes.

BRIEF DESCRIPTION OF DRAWINGS

References are made to the accompanying drawings that form a part of this disclosure and that illustrate embodiments in which the systems and methods described in this Specification can be practiced. Like reference numbers represent the same or similar parts throughout.

FIG. 1 is an exemplary flow chart according to embodiments of methods disclosed herein.

FIG. 2 is a schematic comparative graph showing an exemplary treatment process according to embodiments of methods disclosed herein and a conventional aging process.

DETAILED DESCRIPTION OF DRAWINGS

It is extremely challenging to improve 6xxx series aluminum alloys. The embodiments disclosed herein provide improvements in various properties and/or manufacturing processes.

The present disclosure provides improvements to methods for manufacturing and improved 6xxx series aluminum alloy that are superior to conventional alloys. The alloy composition comprises aluminum (Al), magnesium (Mg), silicon (Si), and one or more additional elements, such as copper (Cu), zinc (Zn), and/or manganese (Mn).

An alloy, such as an aluminum alloy, in particular a 6xxx series aluminum alloy, can be subjected to a solution heat treatment. The solution heat treatment is performed in hopes to obtain a high practical solid solution concentration of the hardening solutes, for example such as Cu, Mg, Si, or Zn. The solubilities of these elements increase markedly with temperature, especially just below the eutectic melting temperature. Consequently, the most favorable temperature for solution treatment is close to an eutectic temperature (e.g., about 5° C. to 8° C. below the eutectic temperature).

FIG. 1 shows a flowchart according to embodiments of a method 100 disclosed herein. The method 100 comprises subjecting an alloy (e.g., aluminum alloy, 6xxx aluminum alloy, etc.) to a solution heat treatment 102 at a particular solution heat treatment temperature. Then, subjecting the alloy to a two-step artificial aging process, which includes a first temperature treatment 104 for a first time duration, and a second temperature treatment 106 for a second time duration. In first temperature treatment 104, a first temperature is applied. The first temperature of the first temperature treatment 104 is greater than an aging hardening temperature of the alloy, while being less than the solution heat treatment temperature used in the solution heat treatment 102. During aging treatment 106, the second temperature can be an aging hardening temperature.

According to some embodiments, the solution heat treatment 102 includes or is followed by a quenching process. According to some embodiments, quenching is performed after the solution heat treatment 102. According to some embodiments, quenching is not performed after the solution heat treatment 102.

According to some embodiments, the aging process does not include a natural aging process. According to some embodiments, the aging process does include a natural aging process. According to some embodiments, the natural aging process is after the first temperature treatment. According to some embodiments, the natural aging process is before the second temperature treatment. According to some embodiments, the natural aging process is after the first temperature treatment, but before the second temperature treatment. According to some embodiments, the natural aging process is from 1 hour to 24 hours. According to some embodiments, the aging process does not include any other conventional artificial aging processes.

In some aspects, the embodiments of the methods described herein can combine any of the following first temperatures, first time durations, second temperatures, and/or second time durations. Accordingly, in some embodiments, the first temperature is 205° C. Accordingly, in some embodiments, the first temperature is from 200° C. to 205° C. Accordingly, in some embodiments, the first temperature is from 205° C. to 210° C. Accordingly, in some embodiments, the first temperature is from 200° C. to 202° C.; 200° C. to 204° C.; 200° C. to 206° C.; 200° C. to 208° C.; or 200° C. to 210° C. Accordingly, in some embodiments, the first temperature is from 202° C. to 204° C.; 202° C. to 206° C.; 202° C. to 208° C.; or 202° C. to 210° C. Accordingly, in some embodiments, the first temperature is from 204° C. to 206° C.; 204° C. to 208° C.; or 204° C. to 210° C. Accordingly, in some embodiments, the first temperature is from 206° C. to 208° C.; or 206° C. to 210° C. Accordingly, in some embodiments, the first temperature is from 208° C. to 210° C. Accordingly, in some embodiments, the first time duration is from 5 minutes to 15 minutes. Accordingly, in some embodiments, the first time duration is from 15 minutes to 20 minutes. Accordingly, in some embodiments, the first time duration is from 5 minutes to 8 minutes; 5 minutes to 10 minutes; 5 minutes to 12 minutes; 5 minutes to 14 minutes; 5 minutes to 16 minutes; 5 minutes to 18 minutes; or 5 minutes to 20 minutes. Accordingly, in some embodiments, the first time duration is from 8 minutes to 10 minutes; 8 minutes to 12 minutes; 8 minutes to 14 minutes; 8 minutes to 16 minutes; 8 minutes to 18 minutes; or 8 minutes to 20 minutes. Accordingly, in some embodiments, the first time duration is from 10 minutes to 12 minutes; 10 minutes to 14 minutes; 10 minutes to 16 minutes; 10 minutes to 18 minutes; or 10 minutes to 20 minutes. Accordingly, in some embodiments, the first time duration is from 12 minutes to 14 minutes; 12 minutes to 16 minutes; 12 minutes to 18 minutes; or 12 minutes to 20 minutes. Accordingly, in some embodiments, the first time duration is from 14 minutes to 16 minutes; 14 minutes to 18 minutes; or 14 minutes to 20 minutes. Accordingly, in some embodiments, the first time duration is from 16 minutes to 18 minutes; or 16 minutes to 20 minutes. Accordingly, in some embodiments, the first time duration is from 18 minutes to 20 minutes. Accordingly, in some embodiments, the second temperature is 175° C. Accordingly, in some embodiments, the second temperature is from 150° C. to 175° C. Accordingly, in some embodiments, the second temperature is from 175° C. to 200° C. Accordingly, in some embodiments, the second temperature is from 150° C. to 160° C.; 150° C. to 170° C.; 150° C. to 180° C.; or 150° C. to 200° C. Accordingly, in some embodiments, the second temperature is from 150° C. to 160° C.; 150° C. to 170° C.; 150° C. to 180° C.; or 150° C. to 200° C. Accordingly, in some embodiments, the second temperature is from 160° C. to 170° C.; 160° C. to 180° C.; or 160° C. to 200° C. Accordingly, in some embodiments, the second temperature is from 170° C. to 180° C.; or 170° C. to 200° C. Accordingly, in some embodiments, the second temperature is from 180° C. to 200° C. Accordingly, in some embodiments, the second time duration is 1 hour. Accordingly, in some embodiments, the second time duration is 2 hours. Accordingly, in some embodiments, the second time duration is 3 hours. Accordingly, in some embodiments, the second time duration is from 30 minutes to 2 hours. Accordingly, in some embodiments, the second time duration is from 2 hours to 3 hours. Accordingly, in some embodiments, the second time duration is from 30 minutes to 40 minutes; 30 minutes to 50 minutes; 30 minutes to 60 minutes; 30 minutes to 70 minutes; 30 minutes to 80 minutes; 30 minutes to 90 minutes; 30 minutes to 100 minutes; 30 minutes to 110 minutes; 30 minutes to 120 minutes; 30 minutes to 130 minutes; 30 minutes to 140 minutes; 30 minutes to 150 minutes; 30 minutes to 160 minutes; 30 minutes to 170 minutes; or 30 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 40 minutes to 50 minutes; 40 minutes to 60 minutes; 40 minutes to 70 minutes; 40 minutes to 80 minutes; 40 minutes to 90 minutes; 40 minutes to 100 minutes; 40 minutes to 110 minutes; 40 minutes to 120 minutes; 40 minutes to 130 minutes; 40 minutes to 140 minutes; 40 minutes to 150 minutes; 40 minutes to 160 minutes; 40 minutes to 170 minutes; or 40 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 50 minutes to 60 minutes; 50 minutes to 70 minutes; 50 minutes to 80 minutes; 50 minutes to 90 minutes; 50 minutes to 100 minutes; 50 minutes to 110 minutes; 50 minutes to 120 minutes; 50 minutes to 130 minutes; 50 minutes to 140 minutes; 50 minutes to 150 minutes; 50 minutes to 160 minutes; 50 minutes to 170 minutes; or 50 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 60 minutes to 70 minutes; 60 minutes to 80 minutes; 60 minutes to 90 minutes; 60 minutes to 100 minutes; 60 minutes to 110 minutes; 60 minutes to 120 minutes; 60 minutes to 130 minutes; 60 minutes to 140 minutes; 60 minutes to 150 minutes; 60 minutes to 160 minutes; 60 minutes to 170 minutes; or 60 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 70 minutes to 80 minutes; 70 minutes to 90 minutes; 70 minutes to 100 minutes; 70 minutes to 110 minutes; 70 minutes to 120 minutes; 70 minutes to 130 minutes; 70 minutes to 140 minutes; 70 minutes to 150 minutes; 70 minutes to 160 minutes; 70 minutes to 170 minutes; or 70 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 80 minutes to 90 minutes; 80 minutes to 100 minutes; 80 minutes to 110 minutes; 80 minutes to 120 minutes; 80 minutes to 130 minutes; 80 minutes to 140 minutes; 80 minutes to 150 minutes; 80 minutes to 160 minutes; 80 minutes to 170 minutes; or 80 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 90 minutes to 100 minutes; 90 minutes to 110 minutes; 90 minutes to 120 minutes; 90 minutes to 130 minutes; 90 minutes to 140 minutes; 90 minutes to 150 minutes; 90 minutes to 160 minutes; 90 minutes to 170 minutes; or 90 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 100 minutes to 110 minutes; 100 minutes to 120 minutes; 100 minutes to 130 minutes; 100 minutes to 140 minutes; 100 minutes to 150 minutes; 100 minutes to 160 minutes; 100 minutes to 170 minutes; or 100 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 110 minutes to 120 minutes; 110 minutes to 130 minutes; 110 minutes to 140 minutes; 110 minutes to 150 minutes; 110 minutes to 160 minutes; 110 minutes to 170 minutes; or 110 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 120 minutes to 130 minutes; 120 minutes to 140 minutes; 120 minutes to 150 minutes; 120 minutes to 160 minutes; 120 minutes to 170 minutes; or 120 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 130 minutes to 140 minutes; 130 minutes to 150 minutes; 130 minutes to 160 minutes; 130 minutes to 170 minutes; or 130 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 140 minutes to 150 minutes; 140 minutes to 160 minutes; 140 minutes to 170 minutes; or 140 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 150 minutes to 160 minutes; 150 minutes to 170 minutes; or 150 minutes to 180 minutes.

Accordingly, in some embodiments, the second time duration is from 160 minutes to 170 minutes; or 160 minutes to 180 minutes. Accordingly, in some embodiments, the second time duration is from 170 minutes to 180 minutes.

After the second temperature treatment 106, the method 100 includes obtaining a resultant alloy 108. Examples of the resultant alloy can include, for example, a 6xxx Al-Si-Mg-Cu aluminum alloys with improved intergranular corrosion (IGC) resistance, which can be manufactured using these embodiments of the methods.

According to some embodiments, improved IGC resistance, as used herein, means a maximum IGC depth of less than 250 μm, an average IGC depth of less than 150 μm, or both.

Accordingly, some embodiments of the aging process includes the following steps:

-   -   1. Subjecting a solution heat treated and quenched 6xxx aluminum         alloy to a temperature above an aging hardening temperature of         the alloy but below the solution heat treatment temperature for         a short period of time (e.g., 205° C. for 16 minutes), and     -   2. Subsequently subjecting the alloy to an aging heat treatment         at the aging hardening temperature for a longer period of time         (e.g., 175° C.) for about 2 hours.

Advantages of the embodiments of the methods disclosed herein include significant cost saving and properties improvement of the resultant alloys. For example, for the A210 extrusion alloy, the embodiments of methods can shorten the aging time from more than 8 hours (conventional aging) to about 3 hours (embodiments of methods). FIG. 2 shows schematically the difference between the method 100 and conventional single step aging process for a 6xxx A210 alloy. The dash line represents the conventional single step aging process, which includes a ramp up to 175° C. in 45 minutes and then soaking at 175° C. for 8 hours. The solid line represents an exemplary method 100 used on the 6xxx A210 alloy. In this example, the method 100 included a ramp up to 205° C. in 45 minutes, soaking the alloy at 205° C. for 16 minutes (first temperature for first time duration), cooling down to 175° C. in about 1 minute, and soaking the alloy at 175° C. for 2 hours (second temperature for second time duration). The total aging time is more than 8.5 hours for the conventional aging process, and only about 3 hours for the method 100 applied in this example.

Clearly, this will significantly reduce the manufacturing time and cost of the A210 extrusion products and thus make the A210 alloy more competitive than other extrusion alloys. The embodiments of methods can also significantly improve the IG corrosion performance of the A210 extrusion alloy without sacrificing other properties, such as bendability or yield strength. Thus, the embodiments disclosed herein provide economic and effective solutions for the IG corrosion issue and can accelerate the application of the A210 alloy.

FIG. 3 summaries some advantages of the disclosed embodiments over a conventional aging process. The embodiments of methods can be used for many 6xxx alloys. Exemplary results are provided below.

EXAMPLE 1 A210 Alloy

Alcoa 6xxx high strength extrusion alloy, A210, was used for to study the effects of the methods disclosed herein. A210 extrusion section had wall thicknesses that vary from 2.5 mm to 4 mm. Extrusion was conducted on a 2500-ton extruder with an extrusion speed around 10 meters per minute. Exit temperature was controlled around 555° C. to 565° C. Extrusion profiles were water quenched with quenching rates in between 50° C./second to 75° C./second. TABLE 1 lists actual composition of A210 alloy evaluated.

TABLE 1 Composition of Exemplary Alcoa High Strength 6xxx A210 Alloy Element Si Mg Cu Fe Mn Cr Ti Others, each Others Total Content, wt % 0.87 0.91 0.55 0.17 0.39 0.17 0.05 0.03 0.1

The A210 Alloy samples were treated via eight different aging processes. The eight processes are detailed in TABLE 2. Process 1 is a conventional aging process generally used for A210 Alloy, wherein the aging takes 8 hours at an aging temperature of 175° C. Processes 2-8 are the artificial aging processes according to the embodiments of the methods disclosed herein, where the first temperature treatment is done for a first time duration, and then a second temperature treatment is done for a second time duration. The total combined time of the first time duration and the second duration can be substantially shorter than the convention time duration (e.g., 8 hours).

TABLE 2 Process 1^(st) Treatment 2^(nd) Treatment 1 Comparative Conventional Aging None Temperature at 175° C. for 8 hours 2 Temperature at 205° C. for 10 minutes Temperature at 175° C. for 2 hours 3 Temperature at 205° C. for 10 minutes Temperature at 175° C. for 4 hours 4 Temperature at 205° C. for 10 minutes Temperature at 175° C. for 6 hours 5 Temperature at 205° C. for 16 minutes Temperature at 175° C. for 1 hour 6 Temperature at 205° C. for 16 minutes Temperature at 175° C. for 2 hours 7 Temperature at 205° C. for 16 minutes Temperature at 175° C. for 4 hours 8 Temperature at 205° C. for 16 minutes Temperature at 175° C. for 6 hours

The resultant alloys from the above eight processes were evaluated. The property evaluations included IG Corrosion and tensile properties. Three tensile specimens and two IG corrosion specimens were used for each condition. Tensile tests were conducted at Westmoreland Mechanical Testing and Research Lab per ASTM E8/E8M specification. lntergranular corrosion tests were conducted per ISO 11846 method B. Measuring and inspecting IG corrosion depth (which are not explicitly described in ISO 11846 method B) was performed as follows. After immersion tests, samples were inspected under stereoscope at 20× magnification. Two sections were marked for each sample to include the most severely attacked locations. After mounting and polishing, sections were viewed under optical microscope. Continuous pictures were taken on both sides of every section. About 18 pictures will cover the whole length of the section (one side). Maximum corrosion depth on each picture was measured. Normal distribution plot can be obtained, maximum and average corrosion depth are then determined. These effects resulting from the eight aging processes on the A210 Alloy mechanical properties and IG corrosion depth are reported in TABLE 3.

TABLE 3 A210 Alloy Mechanical Properties and IG Corrosion Depth Max. IG Average IG Corrosion Corrosion Process UTS, Mpa YS, Mpa E, % Depth, μm Depth, μm 1 396.4 370.2 10.3 246.7 198.4 2 390.0 363.1 10.8 277.7 200.2 3 390.9 369.8 10.7 228.8 159.7 4 393.0 370.0 9.8 280.5 183.4 5 392.7 365.6 9.6 222.6 151.0 6 388.6 364.3 9.6 209.5 139.6 7 387.7 367.2 9.9 235 164.1 8 391.1 366.1 9.6 218.4 137.9 Target >380 >350 >8 <250 <150

TABLE 3 shows the average tensile test results of A210 Alloy for each of the eight different aging processes. It was expected that the conventional aging process, Process 1, would yield a resultant alloy which meets the Target Properties of having greater than 380 MPa tensile strength (UTS), greater than 350 MPa yield strength (YS), and greater than 8% elongation (E).

Surprisingly, Processes 2-8 also can yield resultant alloys that meet the Target Properties of having greater than 380 MPa tensile strength (UTS), greater than 350 MPa yield strength (YS), and greater than 8% elongation (E).

Maximum corrosion depth and average corrosion depth for each aging condition are also shown in TABLE 3. These results show a surprising result, where all two-step aging processes with the 1st step aging at 205° C. for 16 minutes showed better IG corrosion performance than the conventional aging process. Especially, samples aged with Process 6 and Process 8 can meet both maximum corrosion depth and average corrosion depth requirement. In particular, the resultant alloy derived from Process 6 (1st temp. at 205° C. for 16 minutes and 2nd temp. at 175° C. for 2 hours) is more favorable commercially as its total aging cycle time is only 3 hours.

EXAMPLE 2 A210 Alloy With 3.5% Pre-Strain

Alcoa 6xxx high strength extrusion alloy, A210, was used for to study the effects of the methods disclosed herein. A210 extrusion section had wall thicknesses that vary from 2.5 mm to 4 mm. Extrusion was conducted on a 2500-ton extruder with an extrusion speed around 10 meters per minute. Exit temperature was controlled around 555° C. to 565° C. Extrusion profiles were water quenched with quenching rates in between 50° C/second to 75° C/second. TABLE 1 lists actual composition of A210 alloy evaluated. Prior to any aging processes, a 3.5% pre-strain was applied in the extrusion direction for all samples.

The A210 Alloy with 3.5% pre-strain samples were treated via four different aging processes. The four processes are detailed in TABLE 4. Process 1 is a conventional aging process generally used for A210 Alloy, wherein the aging takes 8 hours at an aging temperature of 175° C. Processes 2-4 are the aging processes according to the embodiments of the methods disclosed herein, where the first temperature treatment is done for a first time duration, and then a second temperature treatment is done for a second time duration. In Process 4, a 24 hour natural aging was included between the first temperature treatment and the second temperature treatment. For Processes 2-3, the total combined time of the first time duration and the second duration is substantially shorter than the convention time duration (e.g., 8 hours).

TABLE 4 Process 1^(st) Treatment 2^(nd) Treatment 1 Comparative Conventional Aging None Temperature at 175° C. for 8 hours 2 Temperature at 205° C. for 16 minutes Temperature at 175° C. for 1 hour 3 Temperature at 205° C. for 16 minutes Temperature at 175° C. for 2 hours 4 Temperature at 205° C. for 16 minutes + Temperature at 175° C. for 1 hour natural aging for 24 hours

The resultant alloys from the above four processes were evaluated. The property evaluations included IG corrosion, tensile properties, and a 3-point bending tests. The 3-point bending tests were conducted per VDA 238-100 specifications. The 3-point bending test parameters were as follows. The test results are reported in TABLE 5.

-   -   Sample Length: ˜60 mm     -   Sample width: ˜25 mm     -   Distance between rollers: 6 mm     -   Knife radius: 0.4 mm     -   Roller diameter: 30 mm     -   Velocity to pre-force: 10 mm/min     -   Pre-force: 100 N     -   Test Velocity: 20 mm/min     -   Criteria for test end: max load—4%

TABLE 5 shows some surprising results. Apparently, the embodiments of the methods in this disclosure (Processes 2-4) can significantly improve the IG corrosion performance in the resultant alloy, without obvious detrimental impact on mechanical properties and bending angles. When compared to the conventional aging process (Process 1), Process 3 and Process 4 can significantly improve the IG corrosion performance of the resultant A210 alloy (with 3.5% pre-strain before aging). While Process 2 can also improve the IG corrosion performance, Process 2 did not show a better result than Processes 3 and 4.

TABLE 5 A210 Alloy (with 3.5% pre-strain) Mechanical Properties and IG Corrosion Depth Max. IG Average IG Bending Aging Corrosion Corrosion Angle, time, Process UTS, Mpa YS, Mpa E, % Depth, μm Depth, μm degree hours 1 381.6 365.7 10.3 309 168.1 61.2 8.45 2 382.2 362.4 11.9 251 152.5 59.4 2 3 388.2 371 12 199.5 105.7 59.2 3 4 386.1 371.3 10.1 188.5 110.3 59.8 2.75 (+24) Target >380 >350 >8 <250 <150 >45 <8.45

Among those benefits and improvements that have been disclosed, other objects and advantages of this disclosure will become apparent from the following description taken in conjunction with the accompanying figures. Detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that the disclosed embodiments are merely illustrative of the disclosure that may be embodied in various forms. In addition, each of the examples given regarding the various embodiments of the disclosure which are intended to be illustrative, and not restrictive.

Various aspects are provided below. It will be understood that any of the features stated in the following aspects can be combined with any other aspect.

-   -   Aspect 1. A method comprising:         -   subjecting an alloy to a first temperature for a first time             duration,             -   wherein the first temperature is greater than an aging                 hardening temperature of the alloy and below a solution                 heat treatment temperature; and         -   subjecting the alloy to a second temperature for a second             time duration.     -   Aspect 2. The method of Aspect 1, further comprising:         -   subjecting the alloy to a solution heat treatment at the             solution heat treatment temperature, prior to the subjecting             the alloy to the first temperature.     -   Aspect 3. The method according to any of Aspects 1-2, wherein         the second temperature is an aging hardening temperature.     -   Aspect 4. The method according to any of Aspects 1-3, wherein         the alloy includes a solution heat treated and quenched alloy.     -   Aspect 5. The method according to any of Aspects 1-4, wherein         the alloy includes a 6xxx aluminum alloy.     -   Aspect 6. The method according to any of Aspects 1-5, wherein         the alloy includes a 6xxx Al-Si-Mg-Cu aluminum alloy.     -   Aspect 7. The method according to any of Aspects 1-6, further         comprising:         -   obtaining a resulting alloy,             -   wherein the resulting alloy has an improved                 intergranular corrosion (IGC) resistance.     -   Aspect 8. The method according to any of Aspects 1-7, wherein         the first temperature is from 200° C. to 210° C.     -   Aspect 9. The method according to any of Aspects 1-8, wherein         the first time duration is from 5 minutes to 20 minutes.     -   Aspect 10. The method according to any of Aspects 1-9, wherein         the second temperature is from 150° C. to 200° C.     -   Aspect 11. The method according to any of Aspects 1-10, wherein         the second time duration is from 30 minutes to 3 hours.     -   Aspect 12. A method comprising:         -   subjecting an aluminum alloy to a first temperature for a             first time duration; and         -   subjecting the aluminum alloy to a second temperature for a             second time duration,         -   wherein the first temperature is higher than the second             temperature,         -   wherein the first time duration is from 5 minutes to 20             minutes.     -   Aspect 13. The method according to Aspect 12, wherein the first         temperature is from 200° C. to 210° C.     -   Aspect 14. The method according to any of Aspects 12-13, wherein         the second temperature is from 150° C. to 200° C.     -   Aspect 15. The method according to any of Aspects 12-14, wherein         the second time duration is from 30 minutes to 3 hours.

The terminology used herein is intended to describe embodiments and is not intended to be limiting. The terms “a,” “an,” and “the” include the plural forms as well, unless clearly indicated otherwise. The terms “comprises” and/or “comprising,” when used in this Specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components. As used herein, the term “based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, the meaning of “in” includes “in” and “on.”

It is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size, and arrangement of parts without departing from the scope of the present disclosure. This Specification and the embodiments described are examples, with the true scope and spirit of the disclosure being indicated by the claims that follow. 

1. A method comprising: subjecting an alloy to a first temperature for a first time duration, wherein the first temperature is greater than an aging hardening temperature of the alloy and below a solution heat treatment temperature; and subjecting the alloy to a second temperature for a second time duration.
 2. The method of claim 1, further comprising: subjecting the alloy to a solution heat treatment at the solution heat treatment temperature, prior to the subjecting the alloy to the first temperature.
 3. The method of claim 1, wherein the second temperature is an aging hardening temperature.
 4. The method of claim 1, wherein the alloy includes a solution heat treated and quenched alloy.
 5. The method of claim 1, wherein the alloy includes a 6xxx aluminum alloy.
 6. The method of claim 1, wherein the alloy includes a 6xxx Al-Si-Mg-Cu aluminum alloy.
 7. The method according to claim 1, further comprising: obtaining a resulting alloy, wherein the resulting alloy has an improved intergranular corrosion (IGC) resistance.
 8. The method according to claim 1, wherein the first temperature is from 200° C. to 210° C.
 9. The method according to claim 1, wherein the first time duration is from 5 minutes to 20 minutes.
 10. The method according to claim 1, wherein the second temperature is from 150° C. to 200° C.
 11. The method according to claim 1, wherein the second time duration is from 30 minutes to 3 hours.
 12. A method comprising: subjecting an aluminum alloy to a first temperature for a first time duration; and subjecting the aluminum alloy to a second temperature for a second time duration, wherein the first temperature is higher than the second temperature, wherein the first time duration is from 5 minutes to 20 minutes.
 13. The method according to claim 12, wherein the first temperature is from 200° C. to 210° C.
 14. The method according to claim 12, wherein the second temperature is from 150° C. to 200° C.
 15. The method according to claim 12, wherein the second time duration is from 30 minutes to 3 hours.
 16. The method according to claim 2, further comprising: obtaining a resulting alloy, wherein the resulting alloy has an improved intergranular corrosion (IGC) resistance.
 17. The method according to claim 3, further comprising: obtaining a resulting alloy, wherein the resulting alloy has an improved intergranular corrosion (IGC) resistance.
 18. The method according to claim 4, further comprising: obtaining a resulting alloy, wherein the resulting alloy has an improved intergranular corrosion (IGC) resistance.
 19. The method according to claim 5, further comprising: obtaining a resulting alloy, wherein the resulting alloy has an improved intergranular corrosion (IGC) resistance.
 20. The method according to claim 6, further comprising: obtaining a resulting alloy, wherein the resulting alloy has an improved intergranular corrosion (IGC) resistance. 